These MANLEY NEXTEK valve springs are specially designed to fit the 5.4 Mustang Shelby Cobra engines. The Shelby 5.4 DOHC heads require a special valve spring arrangement because they have two different spring requirements for intake and exhaust. These springs are wound from superclean alloy wire and are a beehive design that will work with the factory retainers and keepers....simply drop these in! They feauture much higher pressure than the factory valve springs so they will withstand huge amounts of boost as well as very high RPM without valve float. A must for modified engines! New retainers can also be used, simply use Manley 221427-32 for titanium replacements.

 

These springs feature the following dimensions: